The availability and cheapness of methane have brought about a demand by the consumers of plants employing methane both for room heating and for sanitary and industrial uses.
The boilers now available on the market present many shortcomings. These originate particularly from the fact that the temperature of free flame methane fuel gases may reach up to 1300.degree.-1950.degree. C. This causes serious problems in connection with the quality of the construction materials, the thermal exchange efficiency, the fuel consumption, the production of obnoxious gases and the safety.